1. Field of the Invention
The present invention relates to a bearing apparatus capable of supporting a load of a structure and of simultaneously moving the structure easily on a plane, and more particularly to a bearing apparatus capable of doing so for a machinery apparatus having a heavy load.
2. Description of the Prior Arts
A prior art ball bearing device is shown in FIG. 6. Ball bearing 10 is made use of as a mechanism for moving, for example, a table supporting a machine, comprising bed 1, table 2 and retainer 4. This device 10 is fixed on floor slab 5, and has a structure (not shown) to be moved which is laid on table 2 and the structure to be moved straight in a longitudinal axial direction on device 10, namely perpendicularly to the plane surface of FIG. 6 of the drawing.
FIG. 7 is a plan view showing schematically another prior art ball bearing device. Ball bearing device 20 has balls 3 placed in a row in retainer 4, the balls being held respectively in holes drilled in the retainer by means of calking the periphery of each of the holes 22. The holes are slightly larger in diameter than the ball. FIG. 8 is a vertical sectional view showing a construction where in balls 3 and retainer 4, having an arrangement illustrated in FIG. 7, work as a bearing. Bearing device 20 is used in such a case by placing the bearing device between foundation 24 and a structure 25 to be moved, the structure 25 being moved in a direction shown by arrow 26 in FIG. 8 by means of an outside force applied to the structure from the side.
FIG. 9 is a vertical sectional view showing schematically a further prior art ball bearing device. Bearing device 30 has number of small balls 32 accomodated in bearer 31 and spherical body 33 placed on the small balls so as to allow the spherical body to freely rotate on the small balls. The small balls are arranged so as to form two layers through a semi-spherically shaped plate 35 inside bearer 31 as shown in FIG. 9. As the spherical body 33 rotates in the direction of arrow 37 shown in FIG. 9 the small balls also circulate in the direction of arrow 38 of FIG. 9 in bearer 31. If a plurality of bearing devices are arranged on floor slab 34 and flat plate 36 is placed on these bearing devices 30, then, the flat plate can be easily moved. Therefore, when a structure (not shown) is put on the flat plate, the structure can also be easily moved. Of course, the structure can be put directly on spherical body 33, dependent on the bottom shape of the structure if the bottom shape is suitable to do so.
Ball bearing devices 10 and 20, however, are disadvantageous in that the usage of these bearing devices is limited because the direction of moving a structure laid on them is limited to one direction. In case of ball bearing device 30, it has drawbacks in that the ball bearing device can not be used by inserting it in a narrow space because it is high in height. In addition, it is expensive because of its complicated constitution.